Daniel Baumgarten

University of Innsbruck | UIBK · Institute of Mechatronics

With its millisecond temporal resolution, Magnetoencephalography (MEG) is well suited for real-time monitoring of brain activity. Real-time feedback allows the adaption of the experiment to the subject’s reaction and increases time efficiency by shortening acquisition and off-line analysis. Two formidable challenges exist in real-time analysis: the...

Magnetic nanoparticles have been widely applied in the nanomedicine field: therapies based on magnetic drug targeting have shown promising results towards the improvement of the current state of the art of medical treatments. Particles interaction with their carrying ow or the surrounding tissues still needs to be completely understood, as well as...

Magnetic nanoparticles (MNP) offer a large variety of promising applications in medicine thanks to their exciting physical properties, e.g., magnetic hyperthermia and magnetic drug targeting. For these applications, it is crucial to quantify the amount of MNP in their specific binding state. This information can be obtained by means of magnetorelax...

Retinal vessels show various biological temporal variations that can impact diagnosis using a static vessel analysis. In this study, Mayer waves in the retinal vessel diameter and arterial blood pressure (BP) signals were characterized, and the temporal correlation between these two modalities was investigated. The arterial and venous vessel diamet...

A dysfunctional vestibular system can be a severe detriment to the quality of life of a patient. Recent studies have shown the feasibility for a vestibular implant to restore rotational sensation via electrical stimulation of vestibular ampullary nerves. However, the optimal stimulation site for selective elicitation of the desired nerve is still u...

As wireless communication systems increasingly require compact and efficient antennas, conventional antenna design methods are proving difficult to meet the rigorous demands of modern applications. For this purpose, this study introduces a methodology which uses pixelated Inverted-F Antenna (IFA) inspired designs optimised through genetic algorithm...

As wireless communication systems increasingly require compact and efficient antennas, conventional antenna design methods are proving difficult to meet the rigorous demands of modern applications. For this purpose, this study introduces a methodology which uses pixelated Inverted-F Antenna (IFA) inspired designs optimised through genetic algorithm...

The analysis of electroencephalography (EEG)/magnetoencephalography (MEG) functional connectivity has become an important tool in neuroscience. Especially the high time resolution of EEG/MEG enables important insight into the functioning of the human brain. To date, functional connectivity is commonly estimated offline, that is, after the conclusio...

Interval Fourier Analysis (-FTA) allows for simultaneous spectral assessment of evoked and spontaneous activity in the frequency domain. We applied this method to signals following peripheral electrical nerve stimulation and performed analysis of cortical somatosensory evoked potentials within the 400 to 750 Hz band. For median nerve stimulation, d...

Magnetic nanoparticles have the potential to be used in various biomedical applications, including magnetic drug targeting and hyperthermia for cancer treatment. In both cases, precise prediction of the local particle concentration is required to plan a successful therapy, which is a challenging task due to several complex flow phenomena. Computati...

Spectral analysis of repeatedly evoked potentials (EPs) is challenging since recordings contain a superposition of evoked signals and spontaneous activity. We developed a novel approach,-interval Fourier Transform Analysis (-FTA), which allows for reliable separation and simultaneous assessment of triggered and background spectral components. Media...

Background: Tele-ophthalmology is gaining recognition for its role in improving eye care accessibility via cloud-based solutions. The Google Cloud Platform (GCP) Healthcare API enables secure and efficient management of medical image data such as high-resolution ophthalmic images. Objectives: This study investigates cloud-based solutions' effect...

Magnetic nanoparticles (MNP) offer exciting biomedical applications, e.g. magnetic hyperthermia for tumor treatment. The knowledge of the quantitative spatial distribution of MNP in the human body is a key for treatment safety and efficiency. Here we experimentally demonstrate the reconstruction of the quantitative MNP distribution of a human head...

Introduction To reliably solve the EEG inverse problem, accurate EEG forward solutions based on a detailed, individual volume conductor model of the head are essential. A crucial—but often neglected—aspect in generating a volume conductor model is the choice of the tissue conductivities, as these may vary from subject to subject. In this study, we...

N-Interval Fourier Transform Analysis (N-FTA) allows for spectral separation of a periodic target signal from uncorrelated background interference. A N-FTA pseudo-code is presented. The spectral resolution is defined by the repetition rate of the near periodic signal. Acceptance criteria for spectral targets were defined such that the probability o...

A feasible and precise method to measure ligament strain during surgical interventions could significantly enhance the quality of ligament reconstructions. However, all existing scientific approaches to measure in vivo ligament strain possess at least one significant disadvantage, such as the impairment of the anatomical structure. Seeking a more a...

Magnetorelaxometry imaging (MRXI) is a non-invasive, quantitative, imaging technique for magnetic nanoparticles (MNPs). The image resolution of this technique significantly depends on the relaxation amplitude (ΔB). For this work, we measured the room temperature (299 K) relaxation signals of eight commercial MNP sample systems with different magnet...

Objective: Magnetorelaxomety imaging (MRXI) is a noninvasive imaging technique for quantitative detection of magnetic nanoparticles (MNPs). The qualitative and quantitative knowledge of the MNP distribution inside the body is a prerequisite for a number of arising biomedical applications, such as magnetic drug targeting and magnetic hyperthermia t...

Background: The integration of innovative imaging technologies into clinical workflows requires the utilization of a standardized data exchange format. The "Digital Imaging and Communications in Medicine" (DICOM) standard is widely used in healthcare to process and transfer medical images. However, no simulation environment is ready to use for dev...

The common spatial pattern (CSP) approach is known as one of the most popular spatial filtering techniques for EEG classification in motor imagery (MI) based brain-computer interfaces (BCIs). However, it still suffers some drawbacks such as sensitivity to noise, non-stationarity, and limitation to binary classification.Therefore, we propose a novel...

The analysis of EEG/MEG functional connectivity has become an important tool in neural research. Especially the high time resolution of EEG/MEG enables important insight into the functioning of the human brain. To date, functional connectivity is commonly estimated offline, i.e., after the conclusion of the experiment. However, online computation o...

b>Hintergrund: Teleophthalmologische Dienstleistungen gelten als geeignet, das Screening, die Frühdiagnose und die Überwachung der wichtigsten Erblindungsursachen auf globaler Ebene zu unterstützen. Hierfür werden Standards und bewährte Verfahren benötigt, um medizinische Augenbilder und zugehörige Daten nahtlos und mit maximaler Interoperabilität...

Magnetic nanoparticles (MNPs) are a promising tool in biomedical applications such as cancer therapy and diagnosis, where localization and quantification of MNP distributions are often mandatory. This can be obtained by magnetorelaxometry imaging (MRXI). In this work, the capability of MRXI for quantitative imaging of MNP inside larger volumes such...

High throughput technologies in genomics enable the analysis of small alterations in gene expression levels. Patterns of such deviations are an important starting point for the discovery and verification of new biomarker candidates. Identifying such patterns is a challenging task that requires sophisticated machine learning approaches. Currently, t...

Color photography is the basis to evaluate ocular surface imaging biomarkers such as eye redness. Different grading scales are hereby used clinically to examine the severity of eye redness ranging from a white to a red eye. Currently used imaging and grading is time consuming and subjective. In this work we propose a baseline pipeline to assess the...

Introduction: Carbohydrate malabsorptions symptoms include intestinal fluid retention, causing diarrhea and abdominal distention. The aim of this work is to create a machine learning model that predicts carbohydrate malabsorption using H 2 measurements from lactose and fructose tolerance tests. Methods: We compare the predictive ability of popular...

The vestibular system is responsible for our sense of balance and spatial orientation. Recent studies have shown the possibility of partially restoring the function of this system using vestibular implants. Electrical modeling is a valuable tool in assisting the development of these implants by analyzing stimulation effects. However, previous model...

Magnetorelaxometry (MRX) of magnetic nanoparticles (MNPs) with optically pumped atomic magnetometers (OPMs) demands very specific and not commonly attainable performance characteristics of the sensors. While calling for ultimate magnetometric sensitivity, magnetorelaxometry relies on the capability of the sensor to detect an MNP sample’s field evol...

Background: Teleophthalmology services are considered capable of supporting screening, early diagnosis, and monitoring of leading causes of blindness on a global scale. Therefore, standards and best practices are needed to seamlessly exchange medical ocular images and related data among relevant stakeholders with maximum interoperability. Objecti...

Background Magnetorelaxometry imaging is an experimental imaging technique capable of reconstructing magnetic nanoparticle distributions inside a volume noninvasively and with high specificity. Thus, magnetorelaxometry imaging is a promising candidate for monitoring a number of therapeutical approaches that employ magnetic nanoparticles, such as ma...

Objective: A number of lumped and distributed parameter models of the inner ear have been proposed in order to improve the vestibular implant stimulation. The models should account for all significant physical phenomena influencing the current propagation: electrical double layer (EDL) and medium polarization. The electrical properties of the medi...

Objective: Magnetorelaxometry imaging is an experimental imaging technique applicable for noninvasive, qualitative and quantitative imaging of magnetic nanoparticles. Accurate reconstructions of nanoparticle distributions are crucial for several novel treatment methods employing magnetic nanoparticles such as magnetic drug targeting or magnetic hy...

Background Spectral analysis of repeatedly evoked potentials (EPs) is challenging since recordings contain a superposition of evoked signals and background activity. We developed a novel approach, N -interval Fourier Transform Analysis ( N -FTA), which allows for reliable separation and accurate assessment of evoked and background spectral componen...

Hydrogen breath tests are a well-established method to help diagnose functional intestinal disorders such as carbohydrate malabsorption or small intestinal bacterial overgrowth. In this work we apply unsupervised machine learning techniques to analyze hydrogen breath test datasets. We propose a method that uses 26 internal cluster validation measur...

Spatial quantitative information about magnetic nanoparticle (MNP) distributions is a prerequisite for biomedical applications like magnetic hyperthermia and magnetic drug targeting. This information can be gathered by means of magnetorelaxometry (MRX) imaging, where the relaxation of previously aligned MNP's magnetic moments is measured by sensiti...

Background: Antitachycardial pacing (ATP) is a painless method for terminating ventricular tachycardias (VT) which would otherwise be treated using a painful high energy shock. However, it is well known that not each VT can be successfully terminated by ATP. Furthermore, ATP can be parametrized in several ways using scan, ramp or scan ramp approac...

Somatosensory evoked potentials are a well-established tool for assessing volley conduction in afferent neural pathways. However, from a clinical perspective, recording of spinal signals is still a demanding task due to the low amplitudes compared to relevant noise sources. Computer modeling is a powerful tool for gaining insight into signal genesi...

To assess the quality of printed solder joints in the jet printing of printed circuit boards, a calibrated camera is used to reconstruct the solder volume via photogrammetry as a specific task of computer vision. This requires a procedure for calibration and orientation determination due to restrictions within the image acquisition process. We here...

Magnetorelaxometry imaging is a highly sensitive technique enabling noninvasive, quantitative detection of magnetic nanoparticles. Electromagnetic coils are sequentially energized, aligning the nanoparticles’ magnetic moments. Relaxation signals are recorded after turning off the coils. The forward model describing this measurement process is refor...

For biomagnetical applications exploiting physical properties of magnetic nanoparticles (MNP), e.g., magnetic hyperthermia, knowledge about the quantitative spatial MNP distribution is crucial, which can be extracted by magnetorelaxometry (MRX) imaging. In this paper, we present quantification, quantitative 1D reconstruction, and quantitative 2D im...

Magnetic nanoparticles have many applications in biomedicine and other technical areas. Despite their huge economic impact, there are no standardised procedures available to measure their basic magnetic properties. The International Organization for Standardization is working on a series of documents on the definition of characteristics of magnetic...

Increasing impedance during freezing might be a valuable marker for guiding cardiac cryo-ablation. We provide model based insights on how decreasing temperature below the freezing point of tissue relates to the percentage of frozen water. Furthermore, we provide experimental data for comparing this percentage with the increase in impedance. Measure...

Magnetic nanoparticles have many applications in biomedicine and other technical areas. Despite their huge economic impact, there are no standardised procedures available to measure their basic magnetic properties. The International Organization for Standardization is working on a series of documents on the definition of characteristics of magnetic...

Magnetic nanoparticles have many applications in biomedicine and other technical areas. Despite their huge economic impact, there are no standardised procedures available to measure their basic magnetic properties. The International Organization for Standardization is working on a series of documents on the definition of characteristics of magnetic...

Magnetorelaxometry imaging is a novel tool for quantitative determination of the spatial distribution of magnetic nanoparticle inside an organism. The use of multiple excitation patterns has been demonstrated to significantly improve spatial resolution. However, increasing the number of excitation patterns is considerably more time consuming, becau...

Background: Machine learning is one important application in the area of health informatics, however classification methods for longitudinal data are still rare. Objectives: The aim of this work is to analyze and classify differences in metabolite time series data between groups of individuals regarding their athletic activity. Methods: We pro...

An 18 years old male patient was diagnosed with genetically confirmed hereditary spastic paraplegia of type SPG11 - a rare disease of neurodegeneration. During normal clinical routine investigation, he presented with a moderate sinus bradycardia. The function of the cardiovascular system was investigated by recording electrocardiogram, impedance ca...

Magnetorelaxometry imaging is a novel tool for quantitative determination of the spatial distribution of magnetic nanoparticles inside an organism. While the use of multiple excitation patterns has been demonstrated to significantly improve spatial resolution, the use of several activation patterns is considerably more time consuming as several exp...

Purpose : The risk for cardiovascular diseases can be evaluated by the measuring of the retinal blood vessel diameters. Temporal variations in vessel diameter lead to uncertainties. Mayer waves are cyclic variations in cardiovascular system, which can be seen in arterial blood pressure. A link to retinal vessel diameters is known in general but tem...

Background: Magnetoencephalography (MEG) and Electroencephalography (EEG) are noninvasive techniques to study the electrophysiological activity of the human brain. Thus, they are well suited for real-time monitoring and analysis of neuronal activity. Real-time MEG/EEG data processing allows adjustment of the stimuli to the subject's responses for...

Stable posture and body movement in humans is dictated by the precise functioning of the ampulla organs in the semi-circular canals. Statistical analysis of the interrelationship between bony and membranous compartments within the semi-circular canals is dependent on the visualization of soft tissue structures. Thirty-one human inner ears were prep...

Flow chart of the modules used in Amira®. The labels were cropped to the size of the SCCs to reduce computing time. Arithmetic modules were used to extract the volumes of the membranous labyrinth, the perilymphatic spaces and a representation for the bony labyrinth. Volumes were then down sampled and thinned by Distance-Ordered Thinner modules. The...

Selected sites of bony labyrinth excision along the centroid of individual specimens. (A) Posterior centerline cut off plane; (B) Superior centerline cut off plane; (C) Lateral centerline cut off plane on the opposite side of the ampulla; (D) Lateral centerline cut off plane on the side of the ampulla; (E) Common crus cut off plane.

Averaged normal vectors of fit planes.

Selected sites of membranous labyrinth excision along the centroid of individual specimens. (A) Posterior ampulla start node; (B) Posterior centerline cut off plane; (C) Superior ampulla start node; (D) Superior centerline cut off plane; (E) Lateral centerline cut off plane on the opposite side of the ampulla; (F) Lateral ampulla start node; (G) La...

Centerlines of 31 manually segmented SCC bony labyrinths aligned along Reid's coordinate system. The average centerlines of all the specimens in bold (green) for the bony labyrinth and dashed lines (red) for the membranous labyrinth. (A) Centerlines of the bony labyrinth on the sagittal plane. (B) Centerlines of the bony labyrinth on the coronal pl...

Cross-sectional area of the bony labyrinth arrayed on the centerline of the bony labyrinth. Shown are the average cross-sectional areas of the bony labyrinth in the posterior SCC (A), superior SCC (B), lateral SCC (C), and the common crus (D). The average area is represented by the red line (bold). Light gray areas indicate the values lying in the...

Extracted cross-sectional images. (A) Cross-sectional image of the perilymphatic space; (B) Membranous labyrinth; (C), and the actual μCT image; (D) Overlay of (A–C).

The aim of this paper is to provide a solid mathematical discussion of the inverse problem in magnetorelaxometry imaging (MRXI), a currently developed technique for quantitative biomedical imaging using magnetic nanoparticles. We provide a detailed discussion of the mathematical modeling of the forward problems including possible ways to magnetical...

The aim of this paper is to provide a solid mathematical discussion of the inverse problem in Magnetorelaxometry Imaging (MRXI), a currently developed technique for quantitative biomedical imaging using magnetic nanoparticles. We provide a detailed discussion of the mathematical modeling of the forward problems including possible ways to activate a...